Field of the Invention
The present invention relates to an occupant determination apparatus in which the weight of an occupant seated on a seat in a vehicle is detected by a load sensor so as to determine any one from a plurality of statuses that are ranges of the weight of the occupant based on the detected measurement weight and acceleration of the vehicle.
Description of Related Art
In the related art, an operation or a non-operation of an air bag system for a front passenger seat of a vehicle, or a deployment speed of the air bag is controlled according to a body size or weight of the occupant seated on the front passenger seat and the presence or absence of the occupant, that is, controlled according to a status. Here, the status is known as four types according to the weight of the occupant: an adult, a child, an infant on a child seat (CRS), an empty seat, or three statuses in which the adult and the child are combined.
The control is performed such that, according to the selected status, for example, in a case where the occupant is the adult or the child, the air bag system operates, and in a case where the occupant is the infant seated on the child seat (CRS) or in a case of the empty seat, the air bag system does not operate.
For example, in the occupant detection device disclosed in Patent Document 1 (Japanese Unexamined Patent Application, First Publication No. 2007-55556), the sum of the load sensors provided on four corners of the seat is determined as weight of the occupant, and the occupant status is determined by comparing the determination threshold value set in advance and the weight of the occupant. In a case where the acceleration of the vehicle is high, the erroneous determination due to the weight shift of the occupant at the time of turning can be prevented by correcting the determination threshold value according to the acceleration or maintaining the determination value up to the previous determination.
In an occupant physique detection device disclosed in Patent Document 2 (Japanese Unexamined Patent Application, First Publication No. 2003-315141), when determining the status by the weight of the occupant, in a case where the number of statuses selected per each unit time, that is, instantaneous status is equal to or more than a predetermined number in a definite time set so as to be longer than the unit time, then the instantaneous status is determined as a final status, so as not to be influenced by the acceleration of the vehicle.
Incidentally, in the vehicle, there is a correlation between a measurement load of the occupant on the front passenger seat and the acceleration of the vehicle. However, the correlation is not the relation of 1:1, but the measured value of the measurement load changes with a delay to a change in acceleration.
For example, as illustrated in FIG. 6, in a case where two load sensors 101 are installed at the front and back of the right side that is one side of a seat 100 in a lateral direction, since an inertial migration of the occupant is generated due to a vehicle movement when the vehicle is turning, the load measured by the load sensor 101 decreases when the vehicle turns left, and increases when turns right. At that time, the weight measured by the load sensor 101 is as illustrated in FIG. 7A, and the acceleration in the lateral direction (referred to as lateral G) measured by an acceleration sensor is as illustrated in FIG. 7B.
As illustrated in FIG. 8, in a case where two load sensors 101 are installed at the back side in a longitudinal direction of the seat 100 (back rest side), the load measured by the load sensors 101 increase when the vehicle is accelerated, and decrease when decelerated due to the inertial migration of the occupant. At that time, the weight measured by the load sensors 101 is as illustrated in FIG. 9A, and the acceleration in the lateral direction (referred to as lateral G) measured by an acceleration sensor is as illustrated in FIG. 9B.